Just 3% of Chennai is safe from flooding, says study

Hyderabad: Just three per cent of Chennai city that comes under the Greater Chennai Corporation (GCC), which is reeling under the effect of Cyclone Michaung, is stated to be safe or at low risk from flooding, according to a study. conducted by a team of geospatial engineers at Anna University.

“Around 30 per cent of the GCC falls under the high-risk category for flooding and around 67 per cent falls under the moderate risk zone,” the study titled Nature Based Solution (NBS) as a Flood Mitigation Measure for Chennai revealed. The study was conducted by Mohammed Faizan, a geospatial engineer, and his team at Anna University.

The study blamed rapid urbanisation, change in land use, and improper drainage system as primary reasons for the flooding.

Speaking to Deccan Chronicle, Faizan said the GCC area was taken up for the study because of its rapid urban expansion and the increasing instances of flooding. The study used 10 parameters such as elevation, slope, flow accumulation, drainage density, topographic wetness index, soil type, annual rainfall, land use land cover (LULC).

"Certain parts have seen rapid progression to urbanisation from green coverage which shows the change in land use and land cover. This aggravated flooding. Furthermore, we found the drainage network not effective in areas near river beds which are mostly slums without proper infrastructure for low-lying spots' ' Faizan added.

He said that during the last 20 years, till 2020, Chennai had seen an increase in built-up land (64.39 per cent), and a decrease in forest land (51.6 per cent) and agricultural land (40.91 per cent). In general, the significant LULC may be attributed to socioeconomic reasons such as population increase, policy decisions related to a rapidly growing economy and reforestation, and physiological characteristics, observed Faizan.

Infographic:

High risk areas: Mambalam, Kodambakkam, Adyar Nungambakkam, Meenambakkam, Velachery and Pallikaranai

Moderate risk areas: Chintadripet, Micro Colony, Besant Theosophical Society

Low risk areas: Ambattur, Bhakthavatchalam Nagar, areas Near Agurchand Manmull Jain College, Chennai.